To meet a demand for radio data traffic that is on an increasing trend since commercialization of a 4th generation (4G) communication system, efforts to develop an improved 5th generation (5G) communication system or a pre-5G communication system have been conducted. For this reason, the 5G communication system or the pre-5G communication system is called a communication system beyond 4G network or a system since the post long-term evolution (LTE).
To achieve a high data transmission rate, the 5G communication system is considered to be implemented in a super high frequency (mmWave) band (e.g., 60 GHz band). To relieve a path loss of a radio wave and increase a transfer distance of a radio wave in the super high frequency band, in the 5G communication system, beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, large scale antenna technologies have been discussed.
Further, to improve a network of the system, in the 5G communication system, technologies such as evolved small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, device to device communication (D2D), wireless backhaul, moving network, cooperative communication, coordinated multi-points (COMP), and interference cancellation have been developed.
In addition to this, in the 5G system, hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC) that are an advanced coding modulation (ACM) scheme and a filter bank multi carrier (FBMC), a non orthogonal multiple access (NOMA), and a sparse code multiple access (SCMA) which are an advanced access technology, and so on have been developed.
The 5G communication system may use beamforming and a terminal (e.g., user equipment (UE)) may measure signal strength of a beam (hereinafter, may be interchangeably used with a beam) transmitted by a base station (eNB, 5G-NB) and may use the measured signal to manage mobility such as a handover, a cell addition, a cell release, and a cell change. The base station may transmit a beam reference signal (BRS), which is a beamformed reference signal, by beam sweeping and the UE may receive a reference signal by the beam sweeping and measure strength, quality, or the like of the reference signal per beam pair to report the measured strength, quality, or the like of the reference signal to the base station. Further, the UE may perform communication using the beam pair having the best signal strength or quality. In the present disclosure, the information generated by allowing the UE to measure the BRS may be called beam measurement information and a transmission beam and a reception beam of the selected beam pair may be said to be aligned with each other.
When the direction of the UE is changed, the directions of the aligned transmission beam and reception beam is misaligned, and therefore communication quality may suddenly deteriorate. Therefore, the UE may change a beam using the beam measurement information. However, to allow the UE to select or change the beam, the reference signals transmitted for all the beams need to be measured by the beam sweeping and a considerable time may be consumed.
Therefore, a method for reducing deterioration in communication quality by reselecting a beam within a short time when the direction of the UE is changed, is desired.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.